My first guesses would be bad camera card, bad cable, bad USB port, poor connection to camera port
Thanks. I tried all of my cameras to see if any issues with importing was the same. All cameras and USB cords are different, but still LR cannot import photos. There are a few blank previews that show up, but they will not import.
Bad USB port?
Can your operating system see the photos on the camera card?
I restarted my computer and all is normal. Possibly getting some more RAM might help. LR is a CPU hog at times.